Integrated busbar and battery connection for electric vehicle battery packs

ABSTRACT

A battery pack for an electric vehicle may include a plurality of battery cells arranged into one or more rows. Each of the plurality of battery cells may include a first terminal and a second terminal, and the plurality of battery cells may include a subset of battery cells with the first terminal oriented in a same direction in the battery pack. The battery pack may also include a busbar configured to conduct electrical energy to and from at least the subset of battery cells. The busbar may include a plurality of cutouts positioned over the first terminals of the subset of battery cells, and a plurality of tabs that springably contact the respective first terminal. A method of building a battery pack with a busbar connection is also presented.

CROSS-REFERENCES TO RELATED APPLICATIONS

The present application is a continuation of U.S. Nonprovisionalapplication Ser. No. 15/187,329, filed Jun. 20, 2016, which is anonprovisional of and claims priority to U.S. Provisional ApplicationNo. 62/272,713, filed Dec. 30, 2015, entitled INTEGRATED BUSBAR ANDBATTERY CONNECTION FOR ELECTRIC VEHICLE BATTERY PACKS, which is relatedto the following commonly assigned patent applications. Each of theseapplications is incorporated herein by reference:

-   -   U.S. Pat. App. No. 62/727,711, filed Dec. 30, 2015, entitled        BATTERY PACKAGING AND INSERT MOLDING FOR ELECTRIC VEHICLES.    -   U.S. Pat. App. No. 62/727,712, filed Dec. 30, 2015, entitled        BATTERY PACKAGING AND INSERT MOLDING FOR ELECTRIC VEHICLES.    -   U.S. Pat. App. No. 62/272,713, filed Dec. 30, 2015, entitled        SMART CHARGING SYSTEM FOR ELECTRIC VEHICLE BATTERY PACKS.

BACKGROUND

An electric vehicle uses one or more electric motors powered byelectrical energy stored in a rechargeable battery pack. Lithium-basedbatteries are often chosen for their high power and energy density. Inorder to ensure that an electric vehicle operates efficiently andsafely, the temperature of the battery pack must be maintained within adefined range of optimal temperatures. The coolant system of electricvehicle can be physically extended to the battery pack to remove excessheat, thereby increasing the service life of the battery pack andincreasing the distance that can be traveled on a single charge.

As the popularity of electric vehicles increases, efficiency in themanufacturing process will become more important. Processes and devicesthat decrease the cost of manufacturing battery packs whilesimultaneously increasing their reliability and safety will be key tomeeting customer demands. Specifically, there is a need for processesand devices that ensure reliable electrical connections betweenindividual battery cells, that efficiently cool the battery pack, andthat aid in the manufacturing process of assembling the thousands ofindividual battery cells into modular packs that can be installed andreplaced when necessary.

BRIEF SUMMARY

In some embodiments, a battery pack for an electric vehicle may includea plurality of battery cells arranged into one or more rows. Each of theplurality of battery cells may include a first terminal and a secondterminal, and the plurality of battery cells may include a subset ofbattery cells with the first terminal oriented in a same direction inthe battery pack. The battery pack may also include a busbar configuredto conduct electrical energy to and from at least the subset of batterycells. The busbar may include a plurality of cutouts positioned over thefirst terminals of the subset of battery cells, and a plurality of tabsthat springably contact the respective first terminal.

In some embodiments, a method of manufacturing a battery pack for anelectric vehicle, may include arranging a plurality of battery cellsinto one or more rows. Each of the plurality of battery cells mayinclude a first terminal and a second terminal, and the plurality ofbattery cells may include a subset of battery cells with the firstterminal oriented in a same direction in the battery pack. The methodmay also include positioning a busbar configured to conduct electricalenergy to and from at least the subset of battery cells. The busbar mayinclude a plurality of cutouts positioned over the first terminals ofthe subset of battery cells, and a plurality of tabs that springablycontact the respective first terminals of the subset of battery cells.

In various embodiments, one or more of the following features may beincluded in any combination and without limitation. Each of theplurality of tabs may be less than 1.0 mm thick. The busbar may includea metal sheet. The plurality of cutouts may be arranged into one or morerows. The plurality of cutouts may be formed by punching holes with atab in a metal sheet. The plurality of cutouts may further be formed bythinning the tab. The plurality of cutouts may further be formed bybending the thinned tab into a springable profile. The busbar may bepositioned on a bottom plane of the battery pack. The busbar may be morethan 1.00 mm thick. The battery pack may further include a second busbarpositioned on a top plane of the battery pack and in contact with thesecond terminal of the subset of battery cells.

BRIEF DESCRIPTION OF THE DRAWINGS

A further understanding of the nature and advantages of the presentinvention may be realized by reference to the remaining portions of thespecification and the drawings, wherein like reference numerals are usedthroughout the several drawings to refer to similar components. In someinstances, a sub-label is associated with a reference numeral to denoteone of multiple similar components. When reference is made to areference numeral without specification to an existing sub-label, it isintended to refer to all such multiple similar components.

FIG. 1 illustrates a simplified diagram of an electric vehicle with arechargeable battery system, according to some embodiments.

FIG. 2 illustrates a lithium-based battery that may be used in electricvehicles, according to some embodiments.

FIG. 3 illustrates a top view and an isometric view of a battery packwith a coolant loop, according to some embodiments.

FIG. 4 illustrates a top view and an isometric view of a battery packwith a coolant loop with a thermal pad that is shaped to conform to thebattery cells.

FIG. 5 illustrates a top view and an isometric view of a section of abusbar with a stamped circular section with a center tab, according tosome embodiments.

FIG. 6 illustrates a side view and an isometric view of a section of abusbar with a thinned center tab, according to some embodiments.

FIG. 7 illustrates a side view and an isometric view of a thinned centertab shaped to springably contact a battery cell terminal, according tosome embodiments.

FIG. 8 illustrates a busbar with a series of cutouts for battery cellsarranged in a plurality of rows, according to some embodiments.

FIG. 9 illustrates a busbar aligned with a plurality of battery cellsarranged in a plurality of rows, according to some embodiments.

FIG. 10 illustrates a busbar mated with a battery pack with a moldedinsert, according to some embodiments.

FIG. 11 illustrates a flowchart of a method of manufacturing a batterypack with a busbar, according to some embodiments.

DETAILED DESCRIPTION

Described herein are embodiments for providing an integrated busbar andconnection apparatus that eliminates solder connections between thebusbar and the terminals of the individual battery cells in a batterypack. In some battery packs, a subset of the battery cells may all beoriented in the same direction such that the positive/negative terminalsare all exposed on the same side of the battery pack (e.g., the bottomof the battery pack). A busbar can be formed by removing a series ofcutouts that are aligned with the individual battery cells. Each cutoutcan include a tab that is thinned and then formed into a springableflange that contacts the terminals of the battery cells. In someembodiments, the busbar can be placed in an injection mold, the batterycells placed thereon, and in molded insert injected to form a solidbattery pack.

FIG. 1 illustrates a simplified diagram 100 of an electric vehicle 102with a rechargeable battery system 104, according to some embodiments.The rechargeable battery system 104 may be comprised of one or morebattery packs 106 a, 106 b, 106 c, 106 d. A battery pack may becomprised of a plurality of individual battery cells that areelectrically connected to provide a particular voltage/current to theelectric vehicle 102. Depending on the embodiment, the electric vehicle102 may include hybrid vehicles that operate using both fuel combustionand stored electric power, as well as fully electric vehicles thatoperate entirely from stored electric power.

The rechargeable battery system 104 represents a major component of theelectric vehicle 102 in terms of size, weight, and cost. A great deal ofeffort goes into the design and shape of the rechargeable battery system104 in order to minimize the amount of space used in the electricvehicle 102 while ensuring the safety of its passengers. In someelectric vehicles, the rechargeable battery system 104 is located underthe floor of the passenger compartment as depicted in FIG. 1. In otherelectric vehicles, the rechargeable battery system 104 can be located inthe trunk or in the hood areas of the electric vehicle.

While a smaller number of larger battery cells could be moreenergy-efficient, the size and cost of of these larger batteries areprohibitive. Furthermore, larger batteries require more contiguousblocks of space in the electric vehicle 102. This prevents largerbatteries from being stored in locations such as the floor of thepassenger compartment as depicted in FIG. 1. Therefore, some embodimentsuse a large number of smaller battery cells that are coupled together togenerate electrical characteristics that are equivalent to single largercells. The smaller cells may be, for example, the size of traditionalAA/AAA batteries, and may be grouped together to form a plurality ofbattery packs 106. Each battery pack may include a large number ofindividual battery cells. In one embodiment, 700 individual lithium-ionbatteries are joined together to form a single battery pack 106 a, andthe rechargeable battery system 104 may include four battery packs 106,eight battery packs, ten battery packs, sixteen battery packs, and/orthe like, connected in parallel or series until the electricalrequirements of the electric vehicle 102 are satisfied. The individualbattery cells included in each battery pack 106 may total in thethousands for a single electric vehicle 102.

FIG. 2 illustrates a diagram 200 of a lithium-based battery 202 that maybe used in electric vehicles, according to some embodiments. As usedherein, the terms “battery”, “cell”, and “battery cell” may be usedinterchangeably to refer to any type of individual battery element usedin a battery system. The batteries described herein typically includelithium-based batteries, but may also include various chemistries andconfigurations including iron phosphate, metal oxide, lithium-ionpolymer, nickel metal hydride, nickel cadmium, nickel-based batteries(hydrogen, zinc, cadmium, etc.), and any other battery type compatiblewith an electric vehicle. For example, some embodiments may use the 6831NCR 18650 battery cell from Panasonic®, or some variation on the 18650form-factor of 6.5 cm×1.8 cm and approximately 45 g. The battery 202 mayhave at least two terminals. In some embodiments, a positive terminal204 may be located at the top of the battery 202, and a negativeterminal 206 may be located on the opposite bottom side of the battery202.

FIG. 3 illustrates a top view 300 and an isometric view 302 of a batterypack 304 with a coolant loop 306, according to some embodiments. Thebattery pack 304 depicted in FIG. 3 is greatly simplified from an actualbattery pack that would be used in electric vehicle. The number ofindividual battery cells and cell rows has been greatly reduced in orderto describe the elements of the present invention simply and clearly. Itwill be understood that actual battery packs would include many moreindividual battery cells and more complicated routing of the coolantloop 306.

The individual battery cells in the battery pack 304 are linearlyarranged in a series of rows, with each individual battery cell beingadjacent to another battery cell within the row. In some embodiments,there will be no appreciable gap between the individual battery cellswithin a single row. In order to maximize the number of individualbattery cells per unit volume, adjacent rows of battery cells are offsetby approximately the radius of one individual battery cell. Adjacentrows are then placed next to each other in the offset position depictedin FIG. 3 such that each individual battery cell in a first row isadjacent to or contacting two individual battery cells in a second row.In some embodiments (not shown) three or more rows are placed adjacentto each other with no appreciable gaps therebetween.

The battery pack 304 of FIG. 3 includes pairs adjacent rows separated bya coolant loop 306. The electric vehicle may be configured to pumpliquid coolant through the coolant loop 306 in order to transfer heatfrom the battery pack 304 to a radiator or other heat exchange system.The coolant loop 306 may include one or more coolant tubes 308 throughwhich liquid coolant may be circulated. In some embodiments, theelectric vehicle may use a dedicated coolant loop for the battery pack304, while other embodiments may utilize an existing engine coolantsystem. In some embodiments, the coolant loop 306 may also be coupled toa heating system, such that the battery pack 304 can be heated whenextreme weather causes the ambient temperature to drop below a preferredoperating temperature range of the individual battery cells.

FIG. 4 illustrates a coolant loop 406 with a thermal pad 410 that isshaped to conform to the battery cells. In this embodiment, the coolantloop 406 is allowed to remain straight, and the thermal interfacebetween the coolant loop 406 and individual battery cells is formedthrough the use of a thermal pad 410. The thermal pad may comprise afirst side that is substantially flat and conforms to the verticalprofile of the coolant loop 406. The thermal pad 410 may be bonded tothe coolant loop 406 using epoxies, adhesives, tape, and/or the like. Insome embodiments, the thermal pad 410 may be manufactured in the form ofthe sleeve with an interior surface that conforms to the shape of thecoolant loop 406. The coolant loop 406 may be inserted into the thermalpad 410 such that the internal surface of the thermal pad 410 is incontact with the coolant loop 406. The thermal pad 410 may be formedfrom a material with at least some elastic properties, thereby causingthe thermal pad 410 to remain in close contact with the coolant loop406.

In the example of FIG. 4, each of the individual battery cells isoriented in a same direction. In other words, the positive terminal ofeach of the individual battery cells faces in an upward directionrelative to the battery pack, and each of the negative terminals facesin a downward direction. In other embodiments, this need not be thecase. Alternating rows of individual battery cells may be oriented inopposite direction such that the positive terminal of a first row isoriented in the up direction and the positive terminal of a second rowis oriented in the downward direction. The orientation pattern forindividual battery cells may vary without limitation. For example, everyother battery cell in a row be oriented in opposite directions. In someembodiments, one half of the battery pack may have battery cellsoriented in one direction, while the other half of the battery pack hascells oriented in the opposite direction. In any of these cases,connections may need to be established between batteries oriented inopposite directions or between batteries oriented in the same direction.

In order to make electrical connections between battery cells, a busbarmay be used. As used herein, the term “busbar” refers to any metallicconductor that is connected to a plurality of individual battery cellterminals in order to transmit power from the individual battery cellsto the electrical system of the electric vehicle. In some embodiments,the busbar may comprise a flat metallic sheet that is positioned on thetop or the bottom of the battery pack. In some embodiments, the metallicsheet may cover an entire top or bottom of the battery pack, while inother embodiments, the busbar may comprise a strip that is longer thanit is wide to interface with a single row of battery cells.

Prior to this disclosure, electrical connections between a busbar and anindividual battery cell was achieved by soldering a wire from theterminal of the battery to the busbar. In the embodiments describedherein, a busbar with an integrated connection tab is presented. In alocation where the busbar interfaces with an individual battery cell, acutout is formed. The cutout may include a center tab that can bethinned and formed into a springable component that is configured tomaintain contact with the terminal of a battery cell.

FIG. 5 illustrates a top view 500 and an isometric view 501 of a section502 of a busbar with a stamped circular section 506 with a center tab504, according to some embodiments. This section 502 of a busbar issimplified for the sake of providing a detailed explanation. Althoughomitted from this figure, the outside shape of the section 502 of thebusbar may extend in each direction to form a metal sheet. The sectionof the busbar may be formed from any metallic or conductive material,such as aluminum. The section 502 of the busbar includes the stampedcircular section 506 with a center tab 504 that may be formed bypressing a cutter into a metal sheet. In some embodiments, the thicknessof the busbar may be between 1.0 mm and 5.0 mm. In one embodiment, thethickness of the busbar is 1.5 mm. Because the stamped circular section506 with the center tab 504 is initially cut from a solid sheet ofmetal, the center tab 504 will initially be the same thickness as therest of the section 502 of the busbar. The shape of the circular section506 is merely exemplary and not meant to be limiting. Other embodimentsmay use cutouts of varying shapes, such as rectangular cutouts, ovalcutouts, and/or the like. These varying shapes may be cut out on amachine press, or may be machined away on a CNC machine.

FIG. 6 illustrates a side view 600 and an isometric view 601 of asection 602 of a busbar with a thinned center tab 604, according to someembodiments. The center tab 504 of FIG. 5 may be formed into aspringable component that can be configured to press against theterminal of the battery cell. In some embodiments, the center tab 504 ofFIG. 5 may simply be bent in a direction of the battery terminal inorder to make contact in a springable fashion. In other embodiments, thecenter tab may be thinned and formed into a shape that provides greaterflexibility than the center tab of the same thickness of the metalsheet. FIG. 6 illustrates a thinned center tab 604 that may be bent andshaped more readily than a center tab of greater thickness.

The thinned center tab 604 may be machined away from the rest of thesection 602 of the busbar within the cutout 606. In embodiments wherethe cutout 606 is machined using a CNC machine, the thinned center tab604 may also be machined to a desired thickness. In some embodiments,the thinned center tab 604 may be between 0.1 mm and 1.0 mm. In oneembodiment, the thinned center tab 604 is approximately 0.3 mm thick. Insome embodiments, the thinned the center tab 604 may be recessed awayfrom the plane of the busbar on one side, while remaining flush with theplane of the busbar on the other side. This allows the busbar to bemachined on a single side without requiring the busbar to be turned overduring the machining process. The thinned center tab 604 may be flushwith the plane of the busbar on the side opposite of the side on whichthe individual battery cells will be positioned.

FIG. 7 illustrates a side view 700 and an isometric view 702 of athinned center tab shaped to springably contact a battery cell terminal,according to some embodiments. The profile of the thinned center tab 704of FIG. 7 is merely exemplary and not meant to be limiting. One havingskill in the art would be able to form many different profiles thatwould have a spreadable characteristic and be flexible enough to makecontact with the individual battery cell terminals.

In this embodiment, the thinned center tab includes a straight section704 followed by an angled section 706 that is of a length sufficient tobring the thinned center tab in contact with the battery terminal on theopposite side of the busbar. The thinned center tab next may include astraight section that provides a mating surface 710 between the busbarand the battery terminal. In some embodiments, the mating surface 710may include a mechanical relief, such as the circular section 708illustrated by FIG. 7. Different shapes may be used in otherembodiments, so long as they bring the thinned center tab 704 in contactwith the battery terminal, and provide a sufficient spring force tomaintain contact between the mating surface 710 and the batteryterminal.

FIG. 8 illustrates a top view 800 and an isometric view 802 of a busbarwith a series of cutouts 806 for battery cells arranged in a pluralityof rows, according to some embodiments. While the previous figures havefocused on a single cutout with a single center tab for simplicity, theviews 800, 802 of FIG. 8 illustrates how the busbar 804 may tend toappear in real-world applications. In this embodiment, each of theindividual battery cells in the section covered by the busbar 804 areoriented in the same direction. For example, a negative terminal of eachof the individual battery cells may be oriented perpendicular to theplane of the busbar 804. Each of the individual battery cells may bepositioned so as to be centered over each of the cutouts 806. Each ofthe cutouts 806 includes a center tab 808 that will make springablecontact with the negative terminal of the individual battery cells.

FIG. 9 illustrates a top isomatric view 900 and a bottom isometric view902 of a busbar 906 aligned with a plurality of battery cells 904arranged in a plurality of rows, according to some embodiments. Theplurality of battery cells 904 is arranged in sets of adjacent rows asillustrated above in FIG. 3, leaving space for a coolant loop to runbetween each of the adjacent pairs of rows of individual battery cells.The cutout sections of the busbar may include a recessed portion thatallows the individual battery cells to be placed within a portion of thecutout. In these embodiments, the busbar 906 may be used as a templatefor placing the individual battery cells so that they are uniform ineach battery pack manufactured. The busbar 906 may also hold theindividual battery cells in place during the manufacturing process suchthat the coolant loop can be routed through the battery pack and anythermal padding or injection-molded inserts can be added without causingthe individual battery cells to shift out of position. As illustrated byview 902, the center tabs of each cutout will make springable contactwith the underside of each of the individual battery terminals withoutrequiring any soldering or other type of mechanical connection.

FIG. 10 illustrates a top isomatric view 1000 and a bottom isometricview 1002 of a busbar 1002 mated with a battery pack with a moldedinsert 1004, according to some embodiments. A molded insert 1004 can beinjected into an injection mold and allowed to flow around and throughany cavities between the individual battery cells and any componentsrelated to the coolant loop. In this embodiment, the molded insert 1004is applied such that it is level with the top of the individual batterycells. The molded insert 1004 fully covers the coolant loop and thethermal pad. However, the molded insert 1004 does not cover the tops ofindividual battery cells or the bottoms of the individual battery cells.Instead, these areas of the individual battery cells are left exposedsuch that electrical connections can be made between individual batterycells after the molded insert is applied. In other embodiments (notshown), the molded insert 1004 does not extend all the way to the topand/or bottom terminals of the battery pack. In some embodiments, theexposed portion of the individual battery cells may be between 1.0 mmand 15.0 mm. The amount of each individual battery cell exposed maydiffer between the top and bottom portions of the individual batterycells. By leaving a portion of the individual battery cells exposed,some types of electrical connections to the individual battery cells maybe more easily applied.

In some embodiments, the injection mold used to apply the molded insert1004 may include room for the busbar 1002. In these embodiments, thebusbar 1002 can be placed within the injection mold. The individualbattery cells can then be added to the cutouts of the busbar 1002, andthe coolant loop can be routed between the rows of individual batterycells and through exit holes in the injection mold. In some embodimentsmay include a second busbar that may be added to the top of the batterypack to connect the positive terminals of the individual battery cells.Note that the second busbar is not shown in FIG. 10 in order to clearlydepict the locations of the individual battery cells relative to thebottom busbar 1002. A combination of plastics and/or epoxies can be theninjected into the injection mold and a solid battery pack can be formed.In some embodiments, the busbar 1002 may be secured to the bottom of thebattery pack by the molded insert or by other mechanical means, such asscrews and/or adhesives.

Although FIG. 10 illustrates a busbar 1002 that is a continuous planethat contacts every battery in the depicted section of the battery pack,other embodiments need not be so limited. As described above, the busbar1002 may be comprised of individual strips of metal that cover singlerows of battery cells. For example, each of the rows of battery cells inFIG. 10 may be oriented in opposite directions, which may require two ormore busbar scripts.

FIG. 11 illustrates a flowchart of a method of manufacturing a batterypack with a busbar, according to some embodiments. The method mayinclude arranging a plurality of battery cells into one or more rows(1102). Each of the plurality of battery cells may include a firstterminal and the second terminal. For example, each cell may include apositive terminal and a negative terminal oriented on opposite sides ofeach of the individual battery cells. The plurality of battery cells mayinclude a subset of battery cells with the first terminal oriented inthe same direction battery pack. For example, a row of battery cells inthe battery pack may form the recited subset of batteries. Each batteryin that row may be oriented such that the positive terminal faces uprelative to the battery pack, and the negative terminal faces downrelative to the battery pack.

The method may also include positioning a busbar configured to conductelectrical energy to and from at least the subset of battery cells(1104). In some embodiments, the busbar may include a plurality ofcutouts positioned over the first terminals of the subset of batterycells. As illustrated above, the cutouts may include recesses into whichthe individual battery cells may be seated such that the battery cellsare centered over the cutout. In some embodiments, the busbar mayinclude a plurality of tabs that springably contact each of the subsetof the battery cells.

It should be appreciated that the specific steps illustrated in FIG. 11provide particular methods of providing a busbar for a battery pack foran electric vehicle according to various embodiments of the presentinvention. Other sequences of steps may also be performed according toalternative embodiments. For example, alternative embodiments of thepresent invention may perform the steps outlined above in a differentorder. Moreover, the individual steps illustrated in FIG. 11 may includemultiple sub-steps that may be performed in various sequences asappropriate to the individual step. Furthermore, additional steps may beadded or removed depending on the particular applications. One ofordinary skill in the art would recognize many variations,modifications, and alternatives.

In the foregoing description, for the purposes of explanation, numerousspecific details were set forth in order to provide a thoroughunderstanding of various embodiments of the present invention. It willbe apparent, however, to one skilled in the art that embodiments of thepresent invention may be practiced without some of these specificdetails. In other instances, well-known structures and devices are shownin block diagram form.

The foregoing description provides exemplary embodiments only, and isnot intended to limit the scope, applicability, or configuration of thedisclosure. Rather, the foregoing description of the exemplaryembodiments will provide those skilled in the art with an enablingdescription for implementing an exemplary embodiment. It should beunderstood that various changes may be made in the function andarrangement of elements without departing from the spirit and scope ofthe invention as set forth in the appended claims.

Specific details are given in the foregoing description to provide athorough understanding of the embodiments. However, it will beunderstood by one of ordinary skill in the art that the embodiments maybe practiced without these specific details. For example, circuits,systems, networks, processes, and other components may have been shownas components in block diagram form in order not to obscure theembodiments in unnecessary detail. In other instances, well-knowncircuits, processes, algorithms, structures, and techniques may havebeen shown without unnecessary detail in order to avoid obscuring theembodiments.

Also, it is noted that individual embodiments may have been described asa process which is depicted as a flowchart, a flow diagram, a data flowdiagram, a structure diagram, or a block diagram. Although a flowchartmay have described the operations as a sequential process, many of theoperations can be performed in parallel or concurrently. In addition,the order of the operations may be re-arranged. A process is terminatedwhen its operations are completed, but could have additional steps notincluded in a figure. A process may correspond to a method, a function,a procedure, a subroutine, a subprogram, etc. When a process correspondsto a function, its termination can correspond to a return of thefunction to the calling function or the main function.

In the foregoing specification, aspects of the invention are describedwith reference to specific embodiments thereof, but those skilled in theart will recognize that the invention is not limited thereto. Variousfeatures and aspects of the above-described invention may be usedindividually or jointly. Further, embodiments can be utilized in anynumber of environments and applications beyond those described hereinwithout departing from the broader spirit and scope of thespecification. The specification and drawings are, accordingly, to beregarded as illustrative rather than restrictive.

What is claimed is:
 1. A busbar for a battery pack in an electricvehicle, the busbar comprising: a sheet of conductive material having afirst thickness configured to conduct electrical energy between aplurality of same terminals on a plurality of battery cells; a pluralityof circular cutouts having diameters that are sized to accept at least aportion of the terminals of the plurality of battery cells inside theplurality of circular cutouts; and a plurality of tabs having a secondthickness configured to springably contact the terminals of theplurality of battery cells, wherein the second thickness is less thanthe first thickness.
 2. The busbar of claim 1, wherein each of theplurality of tabs comprises a straight section coupled to an angledsection that is of a length sufficient to bring the tab into contactwith a battery terminal.
 3. The busbar of claim 2, wherein each of theangled sections is further coupled to a second straight section thatprovides a mating surface between the busbar and the battery terminal.4. The busbar of claim 3, wherein the second straight section comprisesa mechanical relief.
 5. The busbar of claim 4, wherein the mechanicalrelief comprises a semi-circular section.
 6. The busbar of claim 5,wherein the semi-circular section is further coupled to a third straightsection.
 7. The busbar of claim 1, wherein each of the plurality of tabsare less than 1.0 mm thick.
 8. The busbar of claim 1, wherein theplurality of circular cutouts are arranged into one or more rows.
 9. Thebusbar of claim 1, wherein the plurality of circular cutouts are formedby punching holes with a tab in a metal sheet.
 10. The busbar of claim1, wherein the busbar is more than 1.00 mm thick.
 11. A method ofmanufacturing a battery pack for an electric vehicle, the methodcomprising: arranging a plurality of battery cells into one or morerows; and positioning a busbar configured to conduct electrical energyto and from at least the subset of battery cells, the busbar comprising:a sheet of conductive material having a first thickness configured toconduct electrical energy between a plurality of same terminals on theplurality of battery cells; a plurality of circular cutouts havingdiameters that are sized to accept at least a portion of the terminalsof the plurality of battery cells inside the plurality of circularcutouts; and a plurality of tabs having a second thickness configured tospringably contact the terminals of the plurality of battery cells,wherein the second thickness is less than the first thickness.
 12. Themethod of claim 11, wherein each of the plurality of tabs comprises astraight section coupled to an angled section that is of a lengthsufficient to bring the tab into contact with a battery terminal. 13.The method of claim 12, wherein each of the angled sections is furthercoupled to a second straight section that provides a mating surfacebetween the busbar and the battery terminal.
 14. The method of claim 13,wherein the second straight section comprises a mechanical relief. 15.The method of claim 14, wherein the mechanical relief comprises asemi-circular section.
 16. The method of claim 15, wherein thesemi-circular section is further coupled to a third straight section.17. The method of claim 11, wherein each of the plurality of tabs areless than 1.0 mm thick.
 18. The method of claim 11, wherein theplurality of circular cutouts are arranged into one or more rows. 19.The method of claim 11, wherein the plurality of circular cutouts areformed by punching holes with a tab in a metal sheet.
 20. The method ofclaim 11, wherein the busbar is more than 1.00 mm thick.